Unless the OS is rendering the bar off-screen even when there isn't a hardware bar, you could trivially determine whether there is a bar by having the code that controls the bar set a flag / send a message.
For the touch bar, you aren't doing the actual rendering; the OS is. Only the OS knows if there's a touch bar, so without a kext or something, it seems there's no way for you to know if the touch bar exists.
if(!touchbar) return MAKE_SUCCESS_GREAT_AGAIN;